It is a well known fact, that the number of accidents resulting from inattention, tiredness, falling asleep etc. of the driver far exceeds the number of accidents caused by technical faults.
The pertinent statistics are show that in general 70% of the accidents may be attributed to these phenomena. About 20% of the accidents occurring on public roads in USA are the so-called "single-car" accidents, in which no vehicles of transport were taking part beside the vehicle that has undergone the accident. Due to the increased number of vehicles, building of highways, the increase of the volume of transport taking place on public roads and restriction of speed all over the world one may expect an increase of accidents of this type. It has been tried for a long time to ensure the alertness of the driver by means of an expedient "alertness controlling instrument" i.e. in case of decrease in alertness to avert an accident.
In one of the known technical solutions serving for this purpose, previously to the starting of the vehicle an arithmetical task or a task requiring skill is to be performed with the aim to hinder the starting of an extremely tired person or someone, who is influenced by alcohol or medicine. It is obvious that these instruments are absolutely unsuitable for monitoring tiredness in the course of driving.
Several types of equipment have been developed, which monitor tiredness by the cerebral waves, the movement of the eyes or the muscles. All these suppose the wearing of uncomfortable contacts on the body, and as a consequence have not come in general use.
It has been tried to produce stimuli in order to decrease monotony. Such equipment is described in the specification of U.S. Pat. No. 3,611,344 (corresponding to German Pat. No. 2,142,574).This equipment releases periodically repeated stimuli for the driver. The task of the driver lies in extinguishing the signal by using a manual switch. If it does not take place, the equipment stops the ignition of the motor or switches the emergency flashes. The drawback of the solution lies in that the rhythmical stimuli emitted increase monotony and when driving in the city and in dangerous situations the stimuli may divert the attention of the driver.
The equipment used in railways, described in the German Pat. No. 1,199,312, also serves this purpose. This equipment generates a warning signal in dependence of the speed of the vehicle, accordingly in a less foreseeable manner and rhythm; in connection with the so-called "dead-man" switch it is able to sense the decrease of the muscle-tone. Taking into consideration, that this equipment was developed for vehicles travelling on a bounded path--on a railroad--its application in road traffic becomes impossible.
With this last solution the inventions aiming at the production of "awakening" signals reached the limit of their possibilities. Further trials have been directed to the observation of managing the steering-wheel (oscillation). In this case the individual variation of the driving styles involved almost unsolvable problems. It soon became obvious, that the values are depending on the weather, the condition of roads and the technical parameters of the vehicle to such an extent, that the simple counting of oscillation became almost senseless (such solutions have been described in U.S. Pat. Nos. 3,322,639 and 3,106,987.)
The tendency of further development of such equipment is represented by the solution in German Pat. No. 2,404,963. It has been tried--by using the solution described--here to compare the measured oscillation values based on the samples taken in the single sections of the trip, however, this comparison could yield objective values only on long road-sections and with road-surfaces of constant quality.
The solution described in German Pat. No. 2,042,853 continuously controls the quality of the correcting movements beside the oscillation value. If it were possible at all to make all these rapidly or slowly changing parameters (e.g. the angle of inclination of the road, the quality of the tyres, ice, side-wind, the clearance of the steering-wheel, the load of the car etc) into consideration, which qualitatively determine the phenomenon of tiredness, objections could be raised in so far as the instruments mentioned before sense but the final state of the tiredness and do not take into consideration--they are not even able to do it--the peculiar anomalies of steering previous to falling asleep.
The equipment according to U.S. Pat. No. 4,005,398 tries to reduce the chances of superfluous alarms resulting from the incompleteness of the method and involving risks of accident. In this solution essentially the characteristic features of the solutions described in U.S. Pat. Nos. 4,031,527 and 3,322,639 have been combined. The basic principle lies in that the manoeuvres of driving are counted dependent on the speed, simultaneously the oscillation fluctuations of the steering-wheel are also observed. When one or the other of said data falls below the threshold value, an acoustic signal forewarning the driver is given. Thereafter the warning is automatically stopped.
At last--mainly due its original solution--attention should be given to the equipment according to U.S. Pat. No. 3,922,665. This equipment senses the increase of the threshold of hearing. The equipment releases a more and more intense acoustic stimulus for the driver, who has to extinguish the signal at the moment of sensing. Random character of the frequency of the stimuli is ensured by the fact, that the chance of occurrence is a function of the "sensing" period reckoned from the beginning of the generated signal to the moment of extinction. However, the threshold-value of hearing changes at extinction--in most ranges of oscillation--just inversely, (accordingly, it is not increased, but decreased) and its behaviour is influenced by numerous factors (not only by the level of the background-noise, which has been taken in consideration in our invention), that we have almost no other choice, than to assume the view previously described in connection with oscillation of the steering wheel.
As a consequence, the common drawback of the described devices lies in that they do not sense the objective symptoms of tiredness, the stimuli produced with the aim to "shake up" the driver may disturb him in a dangerous situation, besides the devices proposed are too complicated and their universal application is impossible.
The solution described in Hungarian Pat. No. 172,613 more approximates the ergonomically optimal control of alertness. The most important characteristic of said solution lies in that the pulses coming from the sensors of other operating organs of the vehicle connected at other places (and serving for different purposes) are immediately taken up into a function with a "real time"
character, excluding the possibility of diverting the driver's attention. By means of this equipment a more objective phenomenon of tiredness--namely the extension of reaction time--may be controlled, i.e. the period, during which impulses are not received from the operating organs, simultaneously the results are registered by means of suitable auxiliary devices.
However, the drawback of said equipment lies in that the connecting up of the sensors represents a very wearisome task, i.e. when only the minimally needed three points (the brake, and the clutch, the steering-wheel) are connected up, the level of monotony ought to be observed for such a long unit of time, during which failure of attention could not be excluded. This problem pointedly arises in cars, which have different output at different rates of speed. As a further objection it can be stated, that a separate operating organ is needed for the response, while extension of reaction time can be evaluated within rather broad limits only compared to the real biological scale of values.
The most important reason for the necessity for finding a more suitable solution, than those, previously described, lies in that in accordance with the modern theories on monotony the primary reason for tiredness and becoming apathetic may be explained by their "predicted character" beside the lack of stimuli, independent of their rhythm (within wide limits), but depending on the fact, whether always identical, i.e. automatic reflex activity is produced. The solution according Hungarian Pat. No. 172,613--since the period passing till the warning signal is varied within narrow limits and always identical motion--in which reactions are required, cannot serve as an efficient weapon against monotony. Taking into consideration that only one single phenomenon of tiredness is observed, its extent of objectivity can be considered as sufficient only in comparison to other instruments.
The reasons described above led to the endeavor to approach the monitoring of the tiredness of the drivers from a new direction.
Almost every act of the driving process essentially consists of three biological phases: sensing, making a decision and handling.
In order to render this most complicated biological function "measurable" from several points of view, i.e. that we should be able to perform objective qualification, the following tasks have been set when designing the equipment and developing the process:
1. The process according to the invention and the equipment for performing said process should not disturb the activity of the driver while driving, that is, it should perform its function only in traffic situations, when the number of stimuli compelling the driver to handle and the level of driving activity are anyhow low. PA0 2. In an unexpected accident dangerous situation the instrument is not allowed to divert the attention of the driver. PA0 3. In a monotonous situation the instrument should be able to monitor the actual circumstances in such a manner, that a warning signal of unexpected character should be given at random intervals; when sensing said signal, PA0 4. The equipment should give an unambiguous "backward-signal" about the result of the control that the driver should be able to get synchronized with his own state of alertness and in knowledge of the same to choose the speed of driving or to stop. PA0 5. The frequency of the controls should be in compliance with the decreasing or increasing level of alertness of the operator. PA0 6. When sensing tiredness of a critical extent, the equipment should produce warning and alarming signals for calling the attention of the adjacent drivers to the danger or it should be able to stop the vehicle in said dangerous situations. PA0 7. In order to be able to avoid senseless risk on behalf of the driver, the measuring results could be registered by means of suitable auxiliary equipment. PA0 8. In the absence of of suitable auxiliary equipment, the instrument should be able to store at least the dates of the last control (e.g. for routine controls on the public ways, or for informing the authorities). PA0 9. Optionally the equipment could be rendered suitable to hinder the participation of a person who is absolutely unsuitable for driving in traffic, prior to starting, in such a manner that only after having accurately and rapidly performed a task, which can be accomplished in a proper state of alertness only, starting of the vehicle should be possible. PA0 10. Optionally the equipment should be suitable for the protection of property, i.e. it should give an alarm at the unauthorized opening of the parked car (or its trunk) and ignition of the motor (without an alarm) should be allowed only for a person knowing a special series of (electrical) signals. PA0 11. In a monotonous situation the equipment should possibly monitor the extent of alertness of the driver continuously and quite from the beginning. PA0 12. The equipment could be universally used for passenger cars, trucks and working machines, independently of their mode of operation, and an increase of the number of the operating organs of the vehicle should be avoided. PA0 13. Assembly should be simple (and non-professionals should be able to perform it), and low production costs should enable its general and widespread use.
first of all the driver has to interpret the content of the signal, PA1 he has to make the decision about the answer to be given, PA1 responding should take place by a suitably rapid series of motions, which are suitable for being analyzed as to its elements by means of the instrument. PA1 the time elapsing between the beginning of the signal and the appearance of the response voltage expediently with an accuracy of the hundreth of a second, (the so-called reaction time of selection), PA1 the duration of the electric signal between switching of the direction indicator and taking back the same, representing a datum characteristic of the coordination of the series of motions and the quality of the reflexes, and which is especially extended under the influence of alcohol; the identity of the direction of response-motion with that of the instruction is also observed. PA1 the overhasty or confused character of the motion based on the observation, whether the turn signal lever has stopped during displacement backward, or passing the middle, it has given a pulse also to the conductor on the opposite side.
On the basis of the data measured in the described manner, the following data could be defined immediately and electrically:
(a) the reliability of sensing, PA2 (b) the rightness of the decision (compliance with requirements) PA2 (c) the rapidity of the reaction, PA2 (d) the co-ordination of the movements and PA2 (e) the state of the reflexes ensuring finer co-ordination.